#include <iostream>
#include <vector>
#include <algorithm>
#include <math.h>

using namespace std;

bool cmp(pair<long long, long long>& a, pair<long long, long long>& b) {
    return a.second < b.second;
}

int main() {
    long long k;
    cin >> k;
    vector<long long> t;
    vector<long long> s;

    for (long long i = 0; i < k; i++) {
        long long ti;
        cin >> ti;
        t.push_back(ti);
    }
    for (long long i = 0; i < k; i++) {
        long long si;
        cin >> si;
        s.push_back(si);
    }

    vector<pair<long long, long long>> ts;
    for (long long i = 0; i < k; i++) {
        if (s[i] == -1) {
            continue;
        }

        ts.push_back(make_pair(t[i], s[i]));
    }

    sort(ts.begin(), ts.end(), cmp);

    long long c = 1;
    long long sum = 0;
    for (int i = 0; i < ts.size(); i++) {
        sum += ts[i].first;
        int toadd = ceil(sum * 1.0 / ts[i].second - c);
        if (toadd > 0) {
            c += toadd;
        }
    }

    cout << c << endl;

    return 0;
}